Various kinds of waterproof and/or heat insulation sportswear are provided in market for outdoor sports such as hunting, fishing, diving, and etc. In order to ensure waterproof and heat insulation features, sportswear products such as such as waders, diving suits and wetsuits are constructed with various kinds of foam sheet material, such as Neoprene or rubber.
Normally, two side surfaces of the foam sheet are respectively coated with fabric, for example the nylon jersey knit, plush or cotton. Like the production of clothing, a large foam sheet is cut to pieces, which are connected edge to edge to form the wader, diving suit or wetsuit, as shown in FIG. 1. Practically, foam sheet material does not like the general clothing fabric that can be sewn to form the seams. As shown in FIG. 2, a conventional seam structure 10 for connecting two foam sheets 11, 12 together edge to edge is illustrated, wherein the conventional seam structure 10 is constructed by the following steps:
1. Apply adhesive such as neoprene base glue to the two vertical end edges 111, 121 of the two foam sheets 11, 12 respectively.
2. Attach the two end edges 111, 121 of the two foam sheets 11, 12 together.
3. Clamp the two connecting edges 111, 121 together so as to press the two end edges 111, 121 against each other until the two end edges 111, 121 are adhered together.
4. Blind stitch up the one or two end edges 111, 121 to form a stitching seam 13 to reinforce the adhering connection of the two end edges 111, 121 of the two foam sheets 11, 12.
5. Fabric tapes 14 can be glued to cover the stitching seam 13 on either one side or both sides if waterproof feature is required.
In view of the above disclosed conventional seam structure, in order to provide good connection between the two vertical end edges 111, 121 of the two foam sheets 11, 12, the thickness of the foam sheet 11 or 12 must only be varied from 2 mm to 7 mm. No foam sheet thinner than 2 mm can be used because it is extremely difficult to firmly glue such thin end edges together. Therefore, there is no way to reduce the thickness of the whole sportswear product as long as the foam sheets are connected together by the conventional seam structure as shown in FIGS. 1 and 2.
The strength of the conventional seam structure as shown in FIG. 2 is proportional to the gluing area between the end edges 111, 121, i.e. the length of the end edge 111 or 121 times the thickness thereof. In other words, the thickness of the foam sheet 11, 12 determines the connecting strength of the conventional seam structure. The vertical connection between the two end edges 111, 121 is a relatively weak connection, especially when a horizontal force is applied to the foam sheet 11, 12. Therefore, mechanically speaking, the conventional seam structure is not a reasonable structure to provide liable and good connection between foam sheets.